If it weren't for dead guys, we'd probably never have started doing crunches. That's because for years, much of our knowledge of the way muscles work was based on the study of human cadavers. By looking at the anatomy of corpses, modern scientists figured that the function of our abdominal muscles must be to flex the spine. Which is exactly what you do when you perform a crunch, a sit-up, or any other move that requires you to round your lower back. As a result, these exercises were popularized as the best way to work your abs. But the reality is that your abs have a more critical function than flexing your spine: Their main job is to stabilize it. In fact, your midsection muscles are the reason your torso stays upright instead of falling forward due to gravity. So your abs actually prevent your spine from flexing.
The upshot is that if you want better results from your core workout, you need to train your abs for stability. And the best part? You'll hardly have to move.
Your hard-core training plan
Fair warning: This workout may not feel like your usual abs routine. Because the exercises focus on spinal stabilization instead of spinal flexion, they don't create the same type of abdominal-muscle soreness you might feel from traditional core moves. But that doesn't mean they're not working. In fact, since I began using this method in my gym, my clients are seeing faster progress than ever. So don't worry—not only will this workout make your core strong and stable, it'll also make your abs pop. For the best results, do the workout that matches your training level—beginner, intermediate, or advanced—twice a week. Simply perform the exercises below in the order shown, using the prescribed sets, reps, and rest.
Beginner workout
Exercise 1: Plank on Elbows
Assume a pushup position, but with your elbows bent and your weight resting on your forearms. Your body should form a straight line. Now brace your abs as if someone were about to punch you in the gut. Hold for 30 seconds. Rest 30 seconds, and repeat once.
Exercise 2: Mountain Climber with Hands on Bench
In push-up position with your hands on a bench, brace your abs and slowly lift your left knee toward your chest. Pause two seconds, lower it slowly, and then raise your right knee. Alternate for 30 seconds, rest 30, and repeat once.
Exercise 3: Side Plank
Lie on your left side and prop your upper body up on your left forearm. Raise your hips until your body forms a straight line from ankles to shoulders. Now brace your abs and hold for 30 seconds. Roll over onto your right side and repeat. Rest 30 seconds, and do one more set.
Intermediate workout
Exercise 1: Plank with Feet Elevated
Use the guidelines for the beginner version of the exercise, but with both of your feet on a bench.
Exercise 2: Mountain Climber with Hands on Swiss Ball
Follow the beginner instructions, but place your hands on a Swiss ball instead of a bench.
Advanced
Exercise 1: Extended Plank
place your weight on your hands, which should be positioned about 6 to 8 inches in front of your shoulders.
Exercise 2: Swiss-Ball Jackknife
In pushup position with your feet on a Swiss ball, raise your hips and pull the ball forward. Do two sets of 15 reps, with 30 seconds of rest.
Exercise 3: Single-Leg Side Plank
Do the beginner version, but once you're in position, raise your top leg and keep it raised for the duration of the set.